The therapetic armamentarium for Crohn's disease presently includes derivatives of 5-aminosalicylate, corticosteroids, 6-mercaptopureine, azathioprine and methotrexate. These medications, while helpful for many patients, are not effective for all patients. Chronic corticosteriod use is necessary for a large number of patients, who may also suffer any of the multitude of well-known side effects of these drugs. Many continue to have active disease despite even high doses of corticosteroids. The immunodulatory cytokine interleukin-10 may play an important role in the imbalance of cytokines believed to contribute to Crohn's disease. Mucosa of patients with Crohn's disease displays an increase in Th-1- type cytokines and may suffer local effects of exaggerated cel-medited immunity. Interleukin-10, on the other hand, is a Th2-type cytokine believed to be important for downregulating Th1 responses. Pilot studies of a recombinant human Interleukin-10 prepared by Schering- Plough have demonstrated apparent safety and suggestions of efficacy. Studies in non-steroid dependent Crohn's disease and in ulcerative colitis are ongoing (GCRC Protocols 293 and 294). The two submitted protocols are closely related and examine the safety, tolerance and efficacy of repeated subcutaneous dosing with IL-10 in patients with steroid-refractory Crohn's disease. The first protocol provides for an intitial treatment cycle of 28 days, while the second protocol permits retreatment for active disease within 6 months of the first protocol.